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Early VINs: removing the rear squishiness by upgrading suspension components

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FlasherZ

Sig Model S + Sig Model X + Model 3 Resv
Jun 21, 2012
7,030
1,032
Some of us who drive the early-VIN performance cars know of that "squishy" feeling when you accelerate aggressively through turns. The car feels like it rolls, and is missing a firmness in the turn that allows for more positive control in acceleration. Note that I'm not an expert in suspensions by any means, so I'm using the "technical terms". I decided I wanted to find something that would get rid of them.

One owner was able previously to convince Tesla to do a partial upgrade to P85+. I wasn't interested in the stiffer ride of the P85+ so I didn't want to go the entire upgrade route either. I worked with the service center's advisor, who placed the order for the same parts for me. Apparently, it sent up a few red flags and a few folks at corporate reached out to the service advisor asking what we were trying to accomplish. Unfortunately, in the end Tesla declined to do a partial upgrade and stated rather decisively that partial upgrades using P+ components on an originally-delivered P car is not supported, and service centers will not (or no longer) do them. They will do a FULL P+ retrofit at a cost of ~$20k if you so desire, but not a partial upgrade.

However, after consulting with Laurent and lolachampcar, I took a slightly different approach. lolachampcar suggested I just ask them to upgrade the car to the current production specs for P85 cars, with current-rev lower control arms and rear subframe -- that the replacement of just those parts would make the biggest difference in removing the squishies:

The approach that will work with the Service center is-
I would like the sub-frame and lower control arms from the current production P85. They will determine the correct part numbers.
Flasher can speak to the value of the change.

Based on my first P85 (Feb 13 delivery), I believe there is significant merit to changing out just the LCAs if you already have the current production sub-frame. These are inexpensive parts and provide a significant reduction in rear squishiness (a highly technical term). My wife's Sept 13 delivery S85 had these LCAs and it made a significant difference. I was told these LCAs (actually, just updated bushings in the exact same aluminum casting) were first employed in the initial P+ production then migrated to all production MS.

The service center exchanged a few messages with chassis engineering on my requests, and they concurred that the idea would best accomplish what I want, with one other recommendation - a replacement of the upper links as well, which have been revised since the Sig cars. Chassis engineering signed off on the changes and the parts were installed while I was out of town last week. These parts are now common between P85 and P85+ models.

I have to say that I am very, very pleased with the results; the car's ride remains as a sedan should be (so it's not a rock-hard ride) but the squishies are gone under hard acceleration in turns. While turning, the car hangs onto its rear end now.

The price of the change was ~$5k including parts/labor.

Here is the list of parts and the part #'s:

Replace Subframe Assembly - Rear
REAR SUBFRAME ASSY (6007012-00-E) 1.00 1518.69 1,518.69
Replace Control Arm Assembly - Rear - Lower - LH
RR SUSP LCA ASSY (1021416-00-A) 1.00 318.60 318.60
Replace Control Arm Assembly - Rear - Lower - RH
RR SUSP LCA ASSY (1021416-00-A) 1.00 318.60 318.60
Replace Link - Suspension - Rear - Upper - LH
RR SUSP UPPER LINK ASSY (1021418-00-A) 1.00 212.88 212.88
Replace Link - Suspension - Rear - Upper - RH
RR SUSP UPPER LINK ASSY (1021418-00-A) 1.00 212.88 212.88

A big thanks to both Laurent and lolachampcar for their help during the process.

- - - Updated - - -

One other point I should probably note: the service center used to fear having to align my car - they've had to do it several times in the past, due to various issues (initial alignment shift, crazy tire wear, machine specs incorrect, etc.) I was told that in past alignments, it could take them up to 2 hours to get everything aligned, and that in some cases, adjusting something would send everything else out of whack.

After this change, I was told that aligning my car took less than 20 minutes and that everything adjusted very, very nicely. Perhaps my car experienced the same thing that lolachampcar saw in his earlier - the subframe having some weird situation to it that made things not line up quite right.
 
Thanks for sharing this Flasher. I might consider doing this in mine as well.

To those that might ask "why":

Do I need it (for daily driving)? Probably not.
Will I notice it (realistically)? Probably, while participating in autocross and other "high performance driving surface" events.
 
Thanks for sharing this Flasher. I might consider doing this in mine as well.

To those that might ask "why":

Do I need it (for daily driving)? Probably not.
Will I notice it (realistically)? Probably, while participating in autocross and other "high performance driving surface" events.

yeah, ditto. $5k for this is too steep for me to drop but I would like this upgrade. oh well. maybe someone some day will have an aftermarket upgrade of the same quality for a 1/10th of the price.

also, on an unrelated note, I finally got inside wear on my rear tires after 45k miles. not down to the cords yet. the treads were about 4/32" anyway with the 3rd tread at 3/32" so they were about due anyway. the fronts still have 4-5/32" on them though and no inside wear there. I have an appt on Monday to have them rotated to the front and try to get a few thousand more miles out of them before my TSportline 19" grey turbines come in and I planned on upgrading to 255/45ZR19 Michelin Pilot Sport A/S 3's. I need to find a shop that'll swap the TPMS and mount the new wheels/tires.
 
I might need this for my rear end / alignment. I just measured my toe last night and came up with 0.28 out per side. My tires are starting to look like crap(2nd and 3rd sets)and I don't think that my alignment has ever maintained what it should (not sure that service ever specifically did it, didn't see it on the sheet although they did put the updated rear bolts so I assumed it was done) .
 
FlasherZ, thanks so much for sharing this information. This sounds like exactly what the doctor ordered. Can't wait to have it done on mine. I will note, however, that moving to a stagger (245/35/21 front, 285/30/21 rear) setup did change the behavior of my car quite a bit. Possibly it has more to do with the first set of tires I had installed which are Hankook v12s. But in either case, I get a lot less of that weird hesitation/clunking/crumpling feeling when accelerating hard out of turns. Ironically, if it's due to the Hankooks, it is because less traction allows some rear wheel spin (sort of like two wrongs making a right).

I'm going to first upgrade to the now available PSS setup with 245 fronts and 295 rears and then after seeing how the rear end behaves I will see if they will also allow me to do the same upgrade you did. Can't wait to try it!
 
What is the VIN cutoff for this, does anyone know? I'm 16186. I have not noticed any squishiness and my alignment is holding perfect. No wear issues whatsoever, rotation had to be postponed by 2,500 miles to 7,500 miles due to lack of wear.

I don't think we have a collective opinion on when the change occurred. There is a part # sticker, but unfortunately the underbody shields need to be removed in order to see it. My wild guess is sometime probably near the P+ shipping timeframe?
 
If it saves the SC 1.6 hours or work, perhaps it should be a free upgrade to save money in the long term :)

yea really. with the twice-a year "annual" service, giving tesla another $1200 a year in subscription payments should also qualify you for free upgrades like this. perhaps someone can point out the the wording of the "free hardware upgrades" that's written into the service plan to Tesla again...
 
yea really. with the twice-a year "annual" service, giving tesla another $1200 a year in subscription payments should also qualify you for free upgrades like this. perhaps someone can point out the the wording of the "free hardware upgrades" that's written into the service plan to Tesla again...

They are still requiring twice a year service for mileage? I thought they said once a year was fine.
 
They are still requiring twice a year service for mileage? I thought they said once a year was fine.

it's not required. I'm just opting for it because I drive a ridiculous amount of miles... and I'm doing it at "twice" their recommended interval. aka instead of 12,24,36,48k miles, I'm doing it around 24k, 48k, 72k, 96k, etc... I definitely don't think its needs "more frequent" service, but I also don't want to neglect it either as I want them to keep making sure everything works great.
 
yea really. with the twice-a year "annual" service, giving tesla another $1200 a year in subscription payments should also qualify you for free upgrades like this. perhaps someone can point out the the wording of the "free hardware upgrades" that's written into the service plan to Tesla again...

Sorry, I just don't expect Tesla to up-rev my car any time they redesign a new part, whether I'm paying for a service contract or not. In this particular case, my car was operating safely and working as expected. I paid to improve it a bit more.
 
yea really. with the twice-a year "annual" service, giving tesla another $1200 a year in subscription payments should also qualify you for free upgrades like this. perhaps someone can point out the the wording of the "free hardware upgrades" that's written into the service plan to Tesla again...

Actually no such language exists in your service plan. Read the actual contract. The web page where you order states hardware upgrades, but nothing in the actual contract says that. If you want to get upgrades, I would make sure to save a screen shot of the order page to go along with it. Otherwise, the contract itself does not allow for this.
 
Thanks for the update. This is exactly what I would like to have done and forego the entire retrofit. Glad to hear it makes a difference. The "squishy" feeling is the only thing I don't like about the car. Will ask the SC when I get there next week for the shield upgrade.
 
Thanks for the update. This is exactly what I would like to have done and forego the entire retrofit. Glad to hear it makes a difference. The "squishy" feeling is the only thing I don't like about the car. Will ask the SC when I get there next week for the shield upgrade.
I forwarded a link to this thread (when it was just FlasherZ's post) and the official response was: "No, from corporate." YMMV it seems.
 
I forwarded a link to this thread (when it was just FlasherZ's post) and the official response was: "No, from corporate." YMMV it seems.

There is likely a slight difference in how it is positioned. It is true that corporate has informed the service centers that cars may not be partially upgraded to P+'s.

However, if it is framed as bringing it up to current production specs for a new P85 (not P+!) by replacing the LCA's, UCA's, and subframe with the up-to-date part #'s, corporate said yes. I'm told it came from the director of chassis engineering directly.